/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SCOPED_STRING_CHARS_H_included
#define SCOPED_STRING_CHARS_H_included

#include "JNIHelp.h"

// A smart pointer that provides access to a jchar* given a JNI jstring.
// Unlike GetStringChars, we throw NullPointerException rather than abort if
// passed a null jstring, and get will return NULL.
// This makes the correct idiom very simple:
//
//   ScopedStringChars name(env, java_name);
//   if (name.get() == NULL) {
//     return NULL;
//   }
class ScopedStringChars {
public:
    ScopedStringChars(JNIEnv* env, jstring s) : env_(env), string_(s), size_(0) {
        if (s == NULL) {
            chars_ = NULL;
            jniThrowNullPointerException(env, NULL);
        } else {
            chars_ = env->GetStringChars(string_, NULL);
            if (chars_ != NULL) {
                size_ = env->GetStringLength(string_);
            }
        }
    }

    ~ScopedStringChars() {
        if (chars_ != NULL) {
            env_->ReleaseStringChars(string_, chars_);
        }
    }

    const jchar* get() const {
        return chars_;
    }

    size_t size() const {
        return size_;
    }

    const jchar& operator[](size_t n) const {
        return chars_[n];
    }

private:
    JNIEnv* env_;
    jstring string_;
    const jchar* chars_;
    size_t size_;

    // Disallow copy and assignment.
    ScopedStringChars(const ScopedStringChars&);
    void operator=(const ScopedStringChars&);
};

#endif  // SCOPED_STRING_CHARS_H_included
